The long-term goal of this research is to understand how ribosomal proteins and elongation factors function in protein synthesis. Experiments were designed to identify specific amino acid sequences of protein synthesis elongation factors EF-Tu and EF-G, and of ribosomal proteins L2 and L7/12 that are involved in (a) aminoacyl-tRNA binding to the ribosome (EF-Tu); (b) peptidyltransferase activity (L2) and (c) translocation (EF-G, L7/12). "Anti-peptide" monoclonal antibodies of partially predetermined specificity will be generated by immunization of BALB/c mice with carrier-coupled specific fragments and peptides from EF-Tu, EF-G, L2 and L7/12. Hybridoma culture fluids will be screened for the presence of antibodies that (a) recognize the uncleaved protein from which the antigen fragments were derived; (b) recognize the 50S ribosomal subunit; (c) inhibit specific protein synthetic activities (in vitro assays). Positive cultures will be cloned and expanded and the desired antibodies purified from ascites fluid. The protein fragment or peptide recognized by each monoclonal antibody will be identified by electroblotting, competition inhibition ELISA and affinity chromatography. The monoclonal antibodies and Fab fragments thereof will be used to (a) test the effects of blocking the identified amino acid sequence by Fab fragments on protein synthetic activity (defined in vitro assays); (b) to identify the antibody recognized amino acid sequences on the surface of the ribosome by immune electron microscopy; (c) to conduct comparative structural and functional studies with ribosomes from archaebacteria and eukaryotes; (d) to identify and purify cross-linked peptides by affinity chromatography.